Anti-migratory additive for emulsified phenolic resin systems said additive being a water soluble polyacrylate

ABSTRACT

The present invention relates to an anti-migratory (as respects impregnated porous sheet members) phenol-formaldehyde resole resin in water emulsions. The emulsion is rendered anti-migratory (when impregnated into paper through the addition thereto of an anti-migratory agent selected from the group consisting of polyelectrolytes, certain salts of inorganic acids, and combinations thereof. The composition is especially useful in the impregnation of filter paper.

C United States Patent 1 1 1 3,719,616

Ingram, II 1 1 March 6, 1973 2,315,400 3/1943 DAlelio ..260 59 UX [54] ANTI-MIGRATORY ADDITIVE FOR 2,555,605 6/1951 Porter ..260/6 EMULSIFIED PHENOUC RESIN 3,092,595 6/1963 Smith et 81.... ..260/7 x SYSTEMS SAID ADDITIVE BEING A 3,131,086 4/1964 Nyquist et 31.... 260/57 x WATER UBL ACRY 3,288,734 11/1966 Stalego ..260/7 3,326,825, 6/1967 Clougherty et al ..260/7 X [75] Inventor: Woodrow Hayes Ingram, II, l-lamp- 3,342,776 9/1967 Lambuth ..260/7 X d Mass 3,364,167 1/1968 lmai et a1 260/38 X 3,381,054 4/1968 LeBlanc et a1. ..260/839 1 Assignee: Monsanto Companhst Louis, 3,388,587 6/1968 Hara e161 ..260/7X [22] Flled' May 1971 Primary ExaminerI-1oward E. Schain [21] Appl. No.: 142,905 Att0rneyWilliam J. Farrington, James C.

. Logomasini, Neal E. Willis and Donald W. Peterson Related US. Application Data [63] Continuation-impart of Ser. No.'8,679, Feb. 4, 1970, [57] ABSTRACT abandon'id- The present invention relates to an anti-migratory (as respects impregnated porous sheet members) phenol- [52] U.S.C1. ..260/7, 117/143 A, 117/155 L, formaldehyde reso1e resin in water emulsions. The

1 17/155 UA, 260/293, 260/29.6 H, emulsion is rendered anti-migratory (when im- 260/29.6 N, 260/296 MN, 260/29.6 R, pregnated into paper through the addition thereto of 260/296 PM, 260/515 an anti-migratory agent selected from the group con- [51] Int. Cl ..C08g 37/20,C08g 37/32 sisting of polyelectrolytes, certain salts of inorganic [58] Field 61 Search ..260/7, 51.5 acids, and combinations r The composition is I especially useful in the impregnation of filter paper. [56] References Cited v UNITED STATES PATENTS 8 Claims, 3 Drawing Figures PAIENTED 6975 3,719,616

v INITIAL RESIN SYSTEM PARTS ADDITIVE PER IOO PARTS O 5 IO I520 SOLIDS SATURATING SOLUTION ANTI-MIGRATORY ADDI'IIVE FOR EMULSIFIED PHENOLIC RESIN SYSTEMS SAID ADDITIVE BEING A WATER SOLUBLE POLYACRYLATE CROSS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of co-pend- 'ing application Ser. No. 8,679, filed Feb. 4, 1970 and now abandoned.

BACKGROUND OF THE INVENTION 1. Field ofthe Invention The present invention relates to phenolic emulsions. More particularly, the present invention relates to resole phenolic resin in water emulsions containing an anti migratory agent which are used to impregnate cellulosic substrates.

2. Description of the Prior Art Emulsified phenolics are well known to the prior art and have been recommended for use in the paper industry for impregnating substrates and for use as beater additives for a variety of end uses.

When substantially water based phenolics, i.e., either liquid phenolic resoles or emulsified (in water) phenolic resins are used for the impregnation of paper, there is experienced, during a drying operation after paper treatment, a phenomenon known as migration. Thus, the resin tends to physically move from venter regions of a paper sheet to surface regions thereof (i.e. a treated-sheets opposed faces). Thus, in a product sheet member from which volatiles have been removed, the resin tends to be concentrated at or near treated sheet surfaces. Heretofore, this problem has been partially solved by the use of solvent based phenolic resins.

While, for some purposes, resin migration is desirable since there are benefits sometimes achieved by having the phenolic resin near treated paper surfaces, for many purposes, the phenomenon of resin migration presents severe industrial problems since the product treated sheet has a non-uniform resin distribution. For example, resin migration causes loss of strength, reduction in porosity,embrittlement (e.g. poor pleatability), etc. The art, then, has long sought ways of minimizing and even eliminating migration in sheet members treated with emulsifiable phenolic resins.

There has now been discovered a system for minimizing and even substantially eliminating phenolic resin migration in porous woven or non-woven sheet members treated with emulsifiable water based phenolics. Not only does the system of this invention reduce or eliminate phenolic resin migration in treated sheet I SUMMARY OF THE INVENTION The present invention relates to an improvement in phenol-formaldehyde resole resin in water emulsions.

The improvement provides a resulting system with reduced tendency for the resin to migrate (and preferably substantially eliminates migration) when the emulsion is used to treat (e.g. impregnate) a porous sheet member, such as a cellulosic sheet or the like compared to the prior unimproved systems.

I The present invention provides a composition of matter comprising in combination:

A. an emulsified phenol-formaldehyde resole resin system of the type comprising phenol-formaldehyde resin dispersed in aqueous medium; and

B. an anti-migratory agent for the resin system wherein the anti-migratory agent is selected from the group consisting of:

l. Polyelectrolytes selected from the group consisting of: a. acrylic acid homopolymers and copolymers and salts thereof, b. copolymers of maleic anhydride and the halfesters and salts of these copolymers,v 0. acrylamide homopolymers and copolymers, d. copolymers of vinyl esters and carboxylic acids and salts thereof, e. methacrylic. acid homopolymers, copolymers and salts thereof, 2. ammonium and alkali metal salts of hydrochloric and sulfuric acid, 3. combinations of a polyelectrolyte as defined in (1) above and ammonium and alkali metal salts of hydrochloric and sulfuric acid.

The present invention also relates to a method for making an emulsified modified phenolic resole resin system of the type above described anti-migratory (as respects reduced capacity of such resin to migrate in a porous, sheet-like member after impregnation thereof with such system during drying). The method involves the step of admixing with such system (before utilization) an aqueous solution of an anti-migratory agent of the type described above to obtain 0.04 to 20.0 percent by weight of said agent in the emulsion.

The present invention further relates to a sheet member comprising a preformed porous substrate in integral, sheet-like form comprised of fibrous material (organic, inorganic, or mixtures thereof) in a woven, non-woven, or mixed woven and non-woven form, such substrate having been impregnated with an emulsified phenolic resin system of this invention. Typically, such an impregnated sheet member contains from about 3 to weight percent (based on total impregnated sheet member weight) of solids derived from the emulsified phenolic resin system of this invention. Preferably, this impregnated sheet member has such solids substantially uniformly distributed therethrough.

DESCRIPTION OF THE DRAWINGS The present invention is better understood by reference to the attached drawings wherein:

FIG. 1 is an enlarged, vertical, artists diagrammatic, sectional view through a portion of a cellulosic paper sheet member impregnated with an emulsified phenolic resin system of this invention containing anti-migratory additive.

FIG. 2 is a further enlarged view of the sheet member of FIG. 1, some parts thereof broken away and after the volatiles have been removed in a drying operation.

FIG. 3 shows a plot of parts anti-migratory additive solution per 100 parts by weight of initial starting emulsifiable phenolic resin system versus percent total solids present in the product emulsified phenolic resin system containing such additive solution.

Turning to FIG. 1, there is seen illustrated a resin impregnated cellulosic paper sheet member prepared in accordance with the teachings of this invention. Inspection of this vertical sectional view reveals that the resin and other solids derived from the emulsified phenolic system used for treatment are uniformly distributed through the sheet member, and that surprisingly and unexpectedly, after drying there has been substantially no resin migration to upper and lower surfaces of the sheet member during the drying operation to remove volatiles from the treated sheet member. The nonmigratory properties of the emulsions of the present invention are further illustrated by FIG. 2. Even under relatively high magnification; individual fibers of the sheet member of FIG. 1 are observed to be uniformly treated with resin, even though such fibers are taken from the mid-region of the sheet member of FIG. 1. Observe that, while in the emulsion used for treatment, the resin was present in the form of little spherules, in the dried, treated sheet member, the individual fibers appear to be uniformly coated with and impregnated with resin.

FIG. 3 illustrates the quantity of anti-migratory additive of the type described in Example (below) needed to achieve approximately equal non-migration of resin in papers treated with emulsions containing anti-migratory additive at varying solids levels. This curve is only a rough estimate or guide to demonstrate that one should consider changing the weight ratio of anti-migratory additive to emulsifiable phenolic resin if the solids content of the resulting emulsion containing such additive is changed appreciably, assuming that such resulting emulsion is to be used to saturate a paper sheet during treatment (impregnation). Owing to the complex nature of the physical and chemical interrelationships involved, those skilled in the art will appreciate that for treating any particular paper stock with any given emulsion system by some particular treating procedure, the optimum levels of anti-migratory additive for differing emulsion resin solids levels and for differing paper basis weights must be arrived at through experience in order to achieve maximum antimigratory action consistent with other variables present. In general, the concentration of anti-migratory additive in a final emulsion will be in the range of from 0.04 to percent by weight based on the weight of the resin solids.

It is an important feature of the present invention that the anti-migratory additives described herein may be used with the starting emulsions described herein without rendering the product emulsions so unstable that agglomeration results therein at such a rate as to adversely affect or even prevent the uniform impregnation of resin into sheet members. Obviously, unless the anti-migratory additives are compatible with the starting emulsion system, such are of no value whatever in obtaining the desired end result. It is interesting to note, for example, in this connection that, in general, for all levels of concentration of anti-migratory additive in an emulsion below the level indicated by the curve in FIG. 3, substantially no emulsion instability (resin agglomeration) appears to occur, while for concentrations above such level, emulsion instability tends to occur.

PREFERRED EMBODIMENTS Characteristically, in the practice of this invention, there is first prepared an emulsifiable phenolic resin system such as known to those skilled in the art. The preferred emulsifiable phenolics particularly suited for use in this invention are characterized as comprising:

A. from about 50 to weight percent total resin solids with the balance up to weight percent thereof being volatile inert solvent liquids,

B. the solvent liquids comprising (on a 100 weight percent resin system basis) from 0 to about 45 weight percent of an organic liquid boiling in the range from about 30 to C. with the balance up to I00 weight percent thereof being water,

C. the total solids'present in said resin system comprising on a 100 weight percent total solids basis:

1. from about 88 to 99 weight percent ofa phenolformaldehyde resole condensate having a free formaldehyde content of 1.5 percent maximum, which condensate is further characterized as being in a one phase condition, with a water dilutability of from 15 percent to 2,000 percent, based on resin solids, and

2. from about 1 to 12 weight percent of a proteinaceous compound soluble in an aqueous media at a pH offrom 7 to l0.

Optionally and preferably, the resins solids as above described also include from about (on a 100 weight percent total solids basis) 1 to 15 weight percent of urea and/or dicyandiamide (assuming a corresponding or appropriate reduction in this amount of phenol-formaldehyde condensate).

The organic liquid as described above is generally chosen so as to be substantially inert (as respects the solids) and also as chosen so as to be a mutual solvent for both the solids and the water.

The organic liquid can comprise mixtures of differentorganic molecules. Preferred organic liquids comprise lower alkanols (such as ethanol, methanol, isopropanol, etc.) and lower alkanones (such as acetone or methylethyl ketone). The term lower refers to less than 7 carbon atoms per molecule as used herein.

As made, these liquid, emulsifiable resins are characteristically colored, one-phase, clear liquid solutions having a viscosity ranging from about 50 to 10,000 centipoises, the exact viscosity of a given liquid resin depending upon chemical process and product variables used in manufacture. Further characterizing the phenolic resole resin, it is necessary to keep the free formaldehyde content of the resole condensate below 1.5 percent maximum in order to permit and facilitate subsequent blending of the proteinaceous protective colloid (which is described in detail below) with the resole condensate. If the free aldehyde content of the resole condensate is greater than 1.5 percent, gelation of the protective colloid occurs rendering the system non-emulsifiable.

In addition, the phenol-formaldehyde resole condensate must have a water dilutability of from 15 percent to 2,000 percent by weight based on resin solids. Water dilutability is a measure of resin advancement and if dilutability is too high, the resin will not form an emulsion but rather a solution in the solids range previously mentioned. Furthermore, if the degree of water dilutability is too low then the resin system will either require excessively large amounts of organic solvent to insure a homogeneous one phase condition or will have prohibitively short storage life.

Preferred phenol-formaldehyde resole resins are those which are modified with melamine. In one preferred procedure, melamine is added initially with the phenol and formaldehyde and condenses with formaldehyde concurrently with the phenol. In another preferred procedure, the melamine is added after the formaldehyde and phenol have partially methylolated. In another procedure, melamine-formaldehyde condensate separately prepared is added to a phenol-formaldehyde condensate. In general, the resulting melamine modified product contains from about 2 to 25 weight percent of melamine based on 100 parts of phenol.

Melamine modified resins are preferred because of the improved stability found in emulsion prepared from the emulsifiable melamine modified resoles. For example, these emulsions exhibit substantially no sedimentation even upon storage for 6 months at room temperature.

The alkali 'solubilizable proteinaceous compounds used are well known to those of ordinary skill in the art. In general, they are amphoteric but are used in the present invention only at a pH of from 7 to 10.

Suitable aqueous solutions of the proteinaceous compound may therefore be prepared in the presence of alkali and alkaline earth metal hydroxides, ammonium hydroxide, organic amines, e.g., urea, dicyandiamide, triethyl amine, and the like as well as mixturesof the foregoing. The most commonly used proteinaceous materials of this type are casein and soya proteins;

common molecular weights range from 100 to 400- thousand.

For use in the current invention, the emulsifiable resole resins previously described are first converted to resin in water emulsions. Alternately, phenolic emulsions known to the art may be also used providing they exhibit sufficient stabilitywhen subsequently co-mixed with the anti-migratory agents of this invention.

In the preferred case, the clear, one phase, homogeneous, emulsifiable resins previously described may be easily converted to resin in water emulsions by the simple addition of water with sufficient agitation to permit effective blending of the water. This can normally be accomplished with the use of conventional propellor type agitators. Depending upon the degree of dilutability of the emulsifiable resin, i.e., degree of advancement, the formation of phenolic resole emulsion may be first characterized by a slight lowering of viscosity with the formation of a water-in-resin emulsion and a peak viscosity at the point at which the system inverts to a resin in water emulsion. Such is the case with relatively high degree of advancement of emulsifiable resin systems having a relatively low degree of water dilutability, e.g., percent. Alternately, with lower advanced phenolic resole emulsifiable resins, emulsification may be accomplished with no noticeable increase in viscosity and result directly in a resin in water emulsion.

Characteristically, the emulsifiable resins described, form resin in water emulsions at total solids contents ranging from about 5 to 45 percent (as determined by ASTM Test Procedure No. D 1 15-55). Once the resin in water emulsion is formed, it may then be further diluted with water to the desired use solids.

For use in the current invention the emulsified phenolics heretofore described are diluted with water to a specified solids and formulated with the antimigratory agent.

Specifically, in the impregnation of filter paper, normal emulsion resin solids are in the range of 5-30 percent although other solids levels may be used.

The anti-migratory agents of this invention are selected from the group consisting of:

A. water soluble polyelectrolytes selected from the group consisting of:

l. acrylic acid homopolymers and copolymers and salts thereof,

2. copolymers of maleic anhydride and the halfesters and salts of these copolymers,

3. acrylamide homopolymers and copolymers,

4. copolymers of vinyl esters and carboxylic acids and salts of these copolymers,

5. methacrylic acid homopolymers, copolymers and salts thereof,

B. ammonium and alkali metal salts of hydrochloric and sulfuric acid,

C. combinations of a polyelectrolyte as defined in (A) above and ammonium and alkali metal salts of hydrochloric and sulfuric acid.

Specific polyelectrolytes used in the present invention include:

A. polyacrylic acid and ammonium and alkali metal salts of these acids wherein the polyacrylic acid has a weight average molecular weight of at least 2,000. Also contemplated for use in this invention are copolymers of acrylic acid which contain up to 50 percent of a comonomer such as vinyl acetate.

B. copolymers of maleic anhydride wherein the comonomer is a lower alpha olefin containing from two to four carbon atoms such as ethylene, propylene, butylene; a vinyl aromatic monomer such as styrene, chlorostyrene, vinyl toluene, etc.; a vinyl ester such as vinyl formate, vinyl acetate, vinyl propionate, vinyl benzoate. Included also are copolymers of maleic anhydride, wherein up to 50 mole percent of the carboxylic acid groups of the maleic anhydride molecule are esterified with a lower alkyl alcohol such as methanol, ethanol, propanol and butanol. Included also are the ammonia and alkali metal salts of the maleic anhydride copolymers and the ester derivatives of these copolymers.

C. polyacrylamide and poly(acrylamide-acrylic) acid copolymers and the ammonium and alkali metal salts of these copolymers.

D. copolymers of acrylic acid and 2-ethyl hexyl acrylate which are prepared according to the teachings of U.S. Pat. No. 2,945,013 which is incorporated herein by reference.

E. polymethacrylic acid and ammonium and alkali metal salts of these acids wherein the polymethacrylic acid has a weight average molecular weight of at least 2,000. Also contemplated for use in this invention are copolymers of polymethacrylic acid which contain up to 50 percent of a comonomer such as vinyl acetate.

The polyelectrolyte used in the present invention must be sufficiently water soluble so as to provide a solution concentration in the impregnating emulsion in the range of from 0.04 to 20 percent by weight based on the weight of total system solids in the emulsion. Especially preferred anti-migratory agents for use in the present invention are combinations of the foregoing polyelectrolytes with the ammonium and alkali metal salts of hydrochloric and sulfuric acid. Such combinations appear to have a synergistic effect as regards the migration of resin particles. The amount of inorganic salt which would be used in combination with the polyelectrolyte will depend upon the particular polyelectrolyte and inorganic salt used as well as with the particular phenolic resin emulsion and particular impregnation application involved. However, in these synergistic combinations the ratio of polyelectrolyte to inorganic salt is varied from 1:99 to 99:1. Preferably, the ratio of polyelectrolyte to inorganic salt will be in the range of from 95:5 to 5:95. These synergistic combinations will be discussed in greater detail below in the working examples.

One of the more preferred systems is that which use a combination of a polyacrylate and an ammonium or alkali metal salt ofhydrochloric or sulfuric acid. An especially preferred system is a mixture of ammonium chloride or ammonium sulfate and a water soluble polyacrylate.

The water soluble polyacrylate salts used are well known to those of ordinary skill in the art. Molecular weights for such salts can fall in the range of from about 100,000 to 700,000 but higher and lower molecular weights can be employed. Cations for such salts are selected from the group consisting of alkali metals and ammonium. Such a salt characteristically has. a pH of about 8 to 10, and preferably about 8.5 to 9.5, in a 13 weight percent water solution. In addition, such polymer preferably contains at least about. 100 units per molecule of the structure:

Formula I I Further, it is preferred to use a polyacrylate polymer which may contain up to about weight percent per molecule of units of the structure:

Formula II LOHFCH I l izil tent such that there is produced a polymer containing not more than about 10 weight percent residual units of formula II above. One preferred polyacrylate salt polymer for use in the present invention is available commercially under the trade designation Acrysol GS (a trademark of the Rohm & Haas Company for its brand of a sodium salt of polyacrylic acid containing up to about 10 percent of units of formula II above). This polymer salt is available commercially as a water solution having a pH in the range of from about 8.5 to 9.5 at about 13 percent solids and further having a viscosity of approximately 10,000 to 20,000 centipoises.

As indicated above, it is preferred to have also dissolved in such anti-migratory additive solution an ammonium salt of a strong inorganic acid. Concentrations of such ammonium salt in such solution typically range from zero to about 30 weight percent (preferably from about 5 to 20 weight percent).

Any convenient treating technique such as dipping, coating, spraying, or the like, can be used to impregnate cellulosic substrates. After treating, the treated sheet-like material is dried as in air or'an oven to lower the volatiles content and make the treated sheet-like product easily handleable. Usually, the treated sheet-like product is first dried at a temperature below one at which any substantial thermosetting or cross-linking of resin (in the treated substrate sheetlike member) occurs. Thus, common drying temperatures range from about to 175 C. over (inverse) times of from about 1 to 20 minutes, as those skilled in the art appreciate.

Such an intermediate product treated sheet thereafter is usually formed by conventional folding, etc. techniques all well known to those of ordinary skill in the art into a desired configuration. After such a sheet forming operation, the product is subjected to an elevated temperature for a time sufficient to substantially completely thermoset the phenolic resin. Typical curing temperatures range from about to 200C. for 30 minutes, as those skilled in the art appreciate.

Characteristically, it is during the preliminary drying step when solvent and carrier liquids are removed from a treated sheet-like member that resin migration tends to occur, and, in accordance with the teachings of this invention, it is during this drying operation that the anti-migratory characteristics associated with the product emulsified resin systems of this invention are appreciated. Such reduction in resin migration is surprising and unexpected. No special precautions need be observed during the preliminary drying step in order to realize benefit of the anti-migratory action associated with the emulsions of this invention.

Tackiness in a dry but not thermoset sheet member impregnated with an emulsified phenolic resin system of this invention may be reduced or eliminated by using a phenolic resin which is relatively highly advanced.

The following examples are set forth to illustrate more clearly the principles and practices of this invention to one skilled in the art, and they are not intended to be restrictive but merely to be illustrative of the invention herein contained. Unless otherwise stated herein, all parts and percentages are on a weight basis. Also, unless otherwise stated herein, all components and products have physical and chemical characteristics as hereinabove specifically stated and explained.

The following Examples 1 to 14 illustrate suitable emulsifiable liquid phenolic resins adopted for use in the preparation of emulsions suitable for use as starting materials in this invention:

EXAMPLE I The product of this example is a highly advanced, emulsifiable phenolic resin adapted for use with an anti-migratory additive for treating filter paper. Sodium caseinate is the main emulsifier. The following starting materials are used:

MATERIAL PARTS Phenol I 50% Formalin 85 Melamine 50% Caustic Solution (NaOl-l) 1.66 Methanol 4] Water Prilled Urea 6.50 Casein 6.50 50% Caustic Solution (NaOH) 0.38

Phenol, 50 percent formalin, melamine and 50 percent caustic solution are heated under vacuum to atmospheric reflux (temperature ranges from 100 to 103C) The reaction proceeds for 80. minutes after reflux starts. At the end of reflux, the resin is cooled with vacuum and allowed to level at 50 i 2C. under 27 inch vacuum. It is then dehydrated to a refractive index of about 1.60. At the end of dehydration, approximately 41 parts of methanol are charged. Finally, a premixed casein solution is added with agitation. A clear, amber colored fluid results.

Premixing of the casein is accomplished as follows: The urea is dissolved in water and the'casein is added and slurried. After 30 minutes, the caustic solution is added and allowed to mix for 30 minutes. This solution may then be added to the resin. The product resin has a total solids content (measured by ASTM Test Procedure No. D l l5-55) of about 60 percent.

The foregoing resin is emulsified as follows: Water is added to the resin with sufficient agitation to form an emulsion. It is observed that the agitation is sufficient to prevent formation of lumps. First a water in resin emulsion is formed. As water is added, the viscosity increases until the emulsion inverts to a resin in water emulsion, at which point the viscosity decreases with the addition of more water. The product emulsion is observed to be infinitely dilutable with water. The resin in water emulsion is storage stable and mechanically stable. The emulsion is observed to reach a peak viscosity and invert from a water in resin emulsion to a resin in water emulsion at about 42 percent solids (as determined by ASTM Test Procedure No. D l l5-55).

When a resin in water emulsion prepared as just described and having a solids content of about 10 percent (same procedure) is cast onto a glass plate, 5 X 7 inches, and then oven dried at a temperature of about 150C. for 10 minutes, there is produced a thermoset resin film which displays excellent water resistance.

EXAMPLE 2 The procedure and starting materials of Example 1 are repeated except that after the alcohol has been added, but before the casein solution addition, the resin is further advanced by refluxing the system at about C. until the product achieves a gel time of about 7-9 minutes, as determined by using a so-called General Electric Gel Test.

The product resin, when water is similarly added, has properties like those associated with the product of Example l, and, in addition, when a film on glass is similarly cast and air dried at 25C. for 2 hours, the product film is observed to be substantially non-tacky demonstrating that the product resin is substantially free from sticking tendencies on industrial paper treating equipment when this resin is used for paper sheet impregnation. When this air dried film is then oven dried as in Example 1, the product thermoset film is found to display excellent water resistance.

EXAMPLE 3 MATERIAL PARTS Phenol I00 50% Formalin Melamine 5 50% Caustic Solution (NaOl-l) 1.66 Ethanol 5 Water 36 Urea 6.50 Casein 5.40 28% Ammonia .94

This reaction proceeds as in Example 1 except that the methanol solvent is replaced by ethyl alcohol. The protective colloid (casein) is prepared as in Example 1 except that the 50 percent sodium hydroxide is replaced by 3'28 percent ammonia solution. The product resin has a total solids content (measured by ASTM Test ProcedureNo. D 1 15-55) of about 64 percent.

The foregoing resin is emulsified as in Example 1. The product emulsion is observed to be infinitely dilutable with water. The resin in water emulsion is storage stable and mechanically stable. The emulsion is observed to reach a peak viscosity and invert from a water in resin emulsion to a resin in water emulsion at about 45 percent solids (as determined by ASTM Test Procedure No. D 1 l5-55),

When a resin in water emulsion prepared as just described and having a solids content of about 10 percent (same procedure) is cast onto a glass plate 5 X 7 inches and then oven dried at a temperature of. about 150C. for 10 minutes there is produced a thermoset resin film which displays excellent water resistance.

EXAMPLE 4 The following starting materials are used:

Phenol 50% Formalin 85 Melamine 5 50% Caustic Solution (NaOH) L66 Water 36 Urea 6.5 Casein 5.4 28% Ammonia .94

The reaction proceeds as in Example 1 except that the alcohol solvent isreplaced by water resulting in a completely aqueous system. The protective colloid (casein) is prepared as in Example 1 except that the 50 percent sodium hydroxide solution is replaced by a 28 percent ammonia solution. The product resin has a total solids content (measured by ASTM Test Procedure No. D 1 15-55) of about 64 percent.

The foregoing resin is emulsified as in Example 1. The product emulsion is observed to be infinitely dilutable with water. The resin in water emulsion is storage stable and mechanically stable. The emulsion is observed to reach a peak viscosity and inverts from a water in resin emulsion to a resin in water emulsion at about 45 percent solids (as determined by ASTM Test Procedure No. D 115-55). I

When a resin in water emulsion prepared as just described and having a solids content of about 10 percent (same procedure) is cast onto a glass plate 5 X 7 inches and then oven dried at a temperature of about 150C. for minutes, there is produced a thermoset resin film which displays excellent water resistance.

EXAMPLE 5 The starting materials and procedure of Example l are repeated except that the urea is eliminated. There is produced a product emulsifiable resin which, when emulsified by the procedure of Example 1, has inversion characteristics and water resistance characteristics like those of Example 1.

EXAMPLE 6 The starting materials and procedure of Example 1 are repeated except that dicyandiamide is used in place of urea. There is produced a product emulsifiable resin which, when emulsified by the procedure of Example 1, has inversion 'characteristics and water resistance characteristics like those of Example 1.

' EXAMPLE 7 The following starting materials are used:

MATERIAL PARTS Phenol 100 50% Formalin 5 Melamine 5 50% Caustic Solution (NaOl-l) L66 Methanol 4] Water 15 Prilled Urea 6.50 Casein 6.50 28% Ammonia 0.94

EXAMPLE 8 The starting materials and the procedure is the same as in Example 7 except that two parts of sodium dioctyl sulfosuccinate are added to the emulsifiable melamine modified phenol-formaldehyde resin formed.

EXAMPLE 9 The starting materials and the procedure is the same as in Example 7 except that two parts of Carbowax 200 (a registered trademark of the Union Carbide Company) are substituted for the sodium dioctyl sulfosuccinate.

EXAMPLE 10 The following starting materials are used:

MATERIAL PARTS Phenol 50% Formalin 85 Melamine 5 50% Caustic Solution (NaOl-l) 1.66- Methanol 4l Water 15 Prilled Urea 6.50 Casein 6.50 28% Ammonia 0.94

The procedure is the same as in Example 2 except that 28 percent ammonia is used in place of the 50 percent caustic solution.

Product properties are equivalent to those of Example 2. I

EXAMPLE 1 1 Example 1 is repeated here except that 80 parts of formalin are used and the melamine is omitted. The resulting resole condensate is formulated as in Example 1 and used to prepare a resin in water emulsion at about 35 percent solids. The emulsion is diluted with water to about 10 percent solids, cast onto a glass plate, 5 X 7 inches, and then oven dried at a temperature of about C. for 10 minutes to produce a thermoset resin film which displays excellent water resistance.

EXAMPLE 12 the general procedure of Example 2 is repeated here using the resole condensate prepared in Example 11. Air dried films on glass are found to be substantially non-tacky demonstrating that the present resin is substantially free from sticking tendencies on industrial paper treating equipment when this resin is used for paper sheet impregnation. Oven dried films are found to display excellent water resistance.

EXAMPLE 13 In this example the starting materials are the same as those used in Example 1 l. Phenol, 50 percent formalin and 50 percent caustic solution are heated under vacuum to an 80C. reflux. The reaction proceeds for 3 hours after reflux starts. At the end of reflux, the resin is cooled with vacuum and allowed to level at 50 i 2C. under 27 inch vacuum. It is then dehydrated to a refractive index of about 1.60. At the end of dehydration, the premixed casein solution is added with agitation. A clear, amber colored fluid results which has a free formaldehyde content of 1.2 percent and a water I When a resin in water emulsion prepared as just described and having a solids content of about l percent (same procedure) is cast onto a glass plate, X 7 inches, and then oven dried at a temperature of about 150C. for 10 minutes, there is produced a thermoset resin film which displays excellent water resistance.

EXAMPLE 14 The starting materials and procedure of Example ll are repeated except that soya protein replaces the casein used in Example 11. The resulting product is an emulsifiable resin which, when emulsified by the procedure of Example ll, has inversion characteristics and water resistance characteristics like those of Example ll.

The following Examples 15 and 16 illustrate phenol formaldehyde resole emulsions which are formulated with anti-migratory agents, and sheet members treated therewith.

EXAMPLE 15 A solution of the following ingredients is prepared:

MATERIAL PARTS Water 100 Acrysol GS (sodium polyacrylate solution) 100 Ammonium Chloride 24 28% Aqueous Ammonium Hydroxide 5 These ingredients are mixed at room temperature until a homogeneous solution is formed. This product solution forms an anti-migratory additive of this invention suitable for adding to emulsified phenolic systems.

To evaluate the foregoing additive, the following procedure is used:

The phenolic resin systems of Examples 1 through 14 (above) are emulsified with water and adequate agitation (sufficient to prevent lump formation) to form a 13 percent solids, resin in water emulsion. Then to each of these resin in water emulsions is added a dilute solution of the anti-migratory additive of this Example composed of 25 parts of such anti-migratory additive diluted with 133 parts of water per 100 parts of the phenolic resin solids of each such emulsion. The diluted anti-migratory additive is added in each instance with sufficient agitation to avoid any localized concentration of the anti-migratory additive in the phenolic resin in water emulsion.

Each resulting phenolic resin in water emulsion containing its above-described anti-migratory additive is then evaluated for migration by the following procedure:

A sample of 100 pounds basis weight relatively porous automotive-type filter paper, is saturated with each such additive containing emulsion by dipping the paper until each sheet is completely saturated. Each resulting so-saturated sheet is then dried for 15 minutes at 160C. in a circulating air oven. At the end of this time, each sheet is removed and examined for resinmigration. Examination of a cross-section of each soprocessed sheet reveals that the treating resin in each instance is evenly distributed throughout the sheet. Substantially, no resin migration is observed. Control examples which contained no anti-migratory agent exhibited excessive resin migration which seriously affected the performance of the filter paper.

EXAMPLE 16 A solution of the following ingredients is made up of:

MATERIAL PARTS Acrysol GS (sodium polyacrylate solution) 100 Water 1350 These ingredients are mixed at room temperature until a homogeneous solution is formed. This product solution forms an anti-migratory additive of this invention suitable for adding to emulsified phenolic systems.

To evaluate the foregoing additive, the following procedure is used.

A sample of the phenolic resin from Example 15 (above) is emulsified with water and adequate agitation (sufficient to prevent lump formation) to form a 13 percent solids, resin in water emulsion. Then to this sample of so emulsified resin in water emulsion is added parts of the above anti-migratory additive per 250 parts of the 13 percent solids phenolic resin in water emulsion. This anti-migratory additive is added with sufficient agitation to avoid any localized concentration of the anti-migratory additive in the'phenolic resin in water emulsion.

The resulting phenolic resin in water emulsion containing its above-described anti-migratory additive is then evaluated for migration as in Example 15. Examination of a cross-section of each so-processed sheet reveals that the treating resin in each instance is evenly distributed throughout the sheet. Substantially, no resin migration is observed.

EXAMPLES 17 to 25 In the following Examples, emulsions are prepared from the phenolic resins prepared in Example 1. These emulsions are then formulated with various anti-migratory agents and used to impregnate paper as in Exam ple 15, which is subsequently examined for resin migra tion. These examples are tabulated in Table l below.

Resin Water Formulation Emulsion, Antimlgratory parts by agent, parts weight by weight Percent Agent Water solids sodium polyacrylate l 424. 5 100 water 60 ammonium sulfate" 25? Same as in Example 17 181 b rchworms 100 water, 325 17. 2

TABLE L-SUMMARY F EXAMPLES 17 To Ali-Continued Emulsion, I Antimlgratory parts by agent, parts weight by weight Percent Ex. Resin Water Formulation Agent Water solids 1827.5 watler I ii.- id 6. copo ymer o acr cyac M 100 378 ethyl-hexyl acrylate (95-5). n

26 sodium chloride 246 water 23 100 374 6.25 polyaorylamide 35. 6 61.4 11

33 sodium sulfate 5 sodium salt of styrene maleic 24 100 368 anhydride. 154 9. 5

water water 25 100 378 24 ammonium chloride u} 3 n 1 Sodium polyacrylate, available from Rohm & Haas Co. as Acrysol OS. 2 Polyacrylamide available from Dow Chemical Co. as Separan AP-273.

3 Ethylene maleic anhydride available from Monsanto Co. as EMA 31.

Examples 17 to further illustrate some of the variations which are possible in the present invention. Examples 17 to 19 illustrate the inverse relationship that exists between the phenolic resin solids in the emulsion and the amount of anti-migratory agent required. The examples also illustrate some of the wide variations which are possible in the choice of an antimigratory agent. in this regard Examples 17 to 23 illustrate synergistic mixtures of a polyelectrolyte and a salt of hydrochloric or sulfuric acid. in these examples resin migration is significantly less than in Examples 24 and 25 which contain only a single anti-migratory agent. Itshould be noted, however, that Examples, 24 and 25 show a significant improvement in resin migration over control examples which do not contain an anti-migratory agent.

Paper impregnated with the formulated emulsions of Examples 17 to'25 show substantially no resin migration whereas in the control examples which contain no anti-migratory agent there was severe resin migration which adversely affected the performance of the paper.

The phenolic emulsions of the present invention which contain an anti-migratory agent are used to impregnate a wide variety of substrates. Examples of such substrates include fiber glass insulation, fibrous reinforcing elements used in the preparation of laminates and composite articles, cellulosic materials such as paper, cotton, wood, fiber board, particle board, moldingpulp, battery separators, etc. Other uses will become apparent to those skilled in the art upon reading the above specification.

What is claimed is:

1. In an emulsified liquid phenolic resin system of the type comprising spherules of phenolic resin dispersed in aqueous medium, at least about 80 percent of said spherules ranging in maximum dimension from about 0.01 to 0.8 microns, said type further comprising on a 100 weight percent total basis:

A. a .quantity of total solids ranging from about 2 weight percent up to the total weight percent of solids present after an emulsion of water in said phenolic resin inverts to anemulsion of said spherules in water'through water addition,

B. a quantity of organic liquid ranging from about 0.5

to 20 weight percent, and

C. a quantity of water equal to the balance up to 100 weight percent thereof, said total solids comprising on a 100 weight percent total solids basis from about 88 to 99 weight percent of said phenolic resin with the balance up to 100 weight percent being a water soluble dissolved proteinaceous protective colloid in basic form, the improvements which comprise in combination,

a. employing as the said phenolic resin in the said system a melamine modified phenol-formaldehyde resole resin, said resin being characterized by:

1. being water soluble to the extent that it has a water dilutability of not greater than about 2:1, meaning that said resin being such that not greater than 2 volumes of water can be mixed with one volume of resin at a temperature of 24-26C. without causing the mixture to exhibit haziness or milkiness,

. having a formaldehyde to phenol combined mole ratio of from about 0.85 to 3.0,

. having a combined melamine content of from about 2 to 25 weight percent based on 100 parts phenol, and

. having a viscosity in methanol solution at weight percent solids concentration of not greater than about 10,000 centipoises, and

. having dissolved in the water in the said system from about 0.04 to 20 percent by weight based on total solids weight of a water soluble polyacrylate salt, said polyacrylate salt being characterized by:

1. having its cations selected from the group consisting of alkali metals and ammonium,

2. having a molecular weight of from about 3. having a pH of from about 8 to 10 when in a 13 weight percent aqueous solution, and

4. containing at least about units per molecule of the structure:

(based on total solids weight) of a dissolved ammonium salt of hydrochloric or sulfuric acid.

3. The phenolic resin emulsion of claim 1 wherein the said proteinaceous protective colloid is casein.

4. The phenolic resin emulsion of claim 1 wherein the said polyacrylate salt contains in addition up to about weight percent per molecule of units of the structure:

phenolic resin system anti-migratory wherein such system is of the type comprising spherules of melamine modified phenolic resin dispersed in aqueous medium,

at least about 80 weight percent of said spherules ranging in maximum dimension from about 0.01 to 0.8 microns, said type further comprising on a 100 weight percent total basis:

A. a quantity of total solids ranging from about 2 weight percent up to the total weight percent of solids present after an emulsion of water in said phenolic resin inverts to an emulsion of said spherules in water through water addition, B. a quantity of organic liquid ranging from about 0.5

to weight percent, and C. a quantity of water equal to the balance up to 100 weight percent thereof, said total solids comprising on a 100 weight percent total solids basis from about 88 to 99 weight percent of said phenolic resin with the balance up to 100 weight percent being a water soluble, dissolved proteinaceous protective colloid in basic form, said phenolic resin being characterized .by: v 1. being water soluble to the extent that it has a water dilutability of not greaterthan about 2:1, meaning that said resin being such that not greater than 2 volumes of water can be mixed with 1 volume of resin at a temperature of 24 26C. without causing the mixture to exhibit haziness or milkiness,

2. having a formaldehyde to phenol combined mol ratio of from about 0.85 to 3.0,

3. having a combined melamine content of from about 2 to weight percent based on 100 parts phenol, and

4. having a viscosity in methanol solution at ,60 weight percent solids concentration of not greater than about 10,000 centipoises,

the step of admixing with such system an aqueous solution in the amount of from about 0.04 to 20 percent by weight on total system solids weight of a water soluble polyacrylate salt, said polyacrylate salt being charac- CHr-CH l ijl 7. The method of claim 6 wherein said emulsion system additionally contains from 0.4 to about 20 weight percent 0 dissolved ammonium salt of a strong inorganic acid. 

1. In an emulsified liquid phenolic resin system of the type comprising spherules of phenolic resin dispersed in aqueous medium, at least about 80 percent of said spherules ranging in maximum dimension from about 0.01 to 0.8 microns, said type further comprising on a 100 weight percent total basis: A. a quantity of total solids ranging from about 2 weight percent up to the total weight percent of solids present after an emulsion of water in said phenolic resin inverts to an emulsion of said spherules in water through water addition, B. a quantity of organic liquid ranging from about 0.5 to 20 weight percent, and C. a quantity of water equal to the balance up to 100 weight percent thereof, said total solids comprising on a 100 weight percent total solids basis from about 88 to 99 weight percent of said phenolic resin with the balance up to 100 weight percent being a water soluble dissolved proteinaceous protective colloid in basic form, the improvements which comprise in combination, a. employing as the said phenolic resin in the said system a melamine modified phenol-formaldehyde resole resin, said resin being characterized by:
 1. being water soluble to the extent that it has a water dilutability of not greater than about 2:1, meaning that said resin being such that not greater than 2 volumes of water can be mixed with one volume of resin at a temperature of 24*-26*C. without causing the mixture to exhibit haziness or milkiness,
 1. having its catioNs selected from the group consisting of alkali metals and ammonium,
 1. being water soluble to the extent that it has a water dilutability of not greater than about 2:1, meaning that said resin being such that not greater than 2 volumes of water can be mixed with 1 volume of resin at a temperature of 24* -26*C. without causing the mixture to exhibit haziness or milkiness,
 2. having a formaldehyde to phenol combined mol ratio of from about 0.85 to 3.0,
 2. The phenolic resin emulsion of claim 1 containing in addition from 0 up to about 20 weight percent (based on total solids weight) of a dissolved ammonium salt of hydrochloric or sulfuric acid.
 2. having a molecular weight of from about 100,000 to 700,000,
 2. having a formaldehyde to phenol combined mole ratio of from about 0.85 to 3.0,
 3. having a combined melamine content of from about 2 to 25 weight percent based on 100 parts phenol, and
 3. having a pH of from about 8 to 10 when in a 13 weight percent aqueous solution, and
 3. The phenolic resin emulsion of claim 1 wherein the said proteinaceous protective colloid is casein.
 3. having a combined melamine content of from about 2 to 25 weight percent based on 100 parts phenol, and
 4. The phenolic resin emulsion of claim 1 wherein the said polyacrylate salt contains in addition up to about 10 weight percent per molecule of units of the structure:
 4. containing at least about 100 units per molecule of the structure:
 4. having a viscosity in methanol solution at 60 weight percent solids concentration of not greater than about 10,000 centipoises, and b. having dissolved in the water in the said system from about 0.04 to 20 percent by weight based on total solids weight of a water soluble polyacrylate salt, said polyacrylate salt being characterized by:
 4. having a viscosity in methanol solution at 60 weight percent solids concentration of not greater than about 10,000 centipoises, the step of admixing with such system an aqueous solution in the amount of from about 0.04 to 20 percent by weight on total system solids weight of a water soluble polyacrylate salt, said polyacrylate salt being characterized by: a. having its cations selected from the group consisting of alkali metals and ammonium, b. having a molecular weight of from about 100,000 to 700,000, c. having a pH of from about 8 to 10 when in a 13 weight percent aqueous solution, and d. containing at least about 100 units per molecule of the structure:
 5. The phenolic resin emulsion of claim 1 containing in addition from 0 up to about 5 weight percent (based on total weight of said phenolic resin) of a surfactant selected from the group consisting of anionic and nonionic surfactants.
 6. In a method for making an emulsified liquid phenolic resin system anti-migratory wherein such system is of the type comprising spherules of melamine modified phenolic resin dispersed in aqueous medium, at least about 80 weight percent of said spherules ranging in maximum dimension from about 0.01 to 0.8 microns, said type further comprising on a 100 weight percent total basis: A. a quantity of total solids ranging from about 2 weight percent up to the total weight percent of solids present after an emulsion of water in said phenolic resin inverts to an emulsion of said spherules in water through water addition, B. a quantity of organic liquid ranging from about 0.5 to 20 weight percent, and C. a quantity of water equal to the balance up to 100 weight percent thereof, said total solids comprising on a 100 weight percent total solids basis from about 88 to 99 weight percent of said phenolic resin with the balance up to 100 weight percent being a water soluble, dissolved proteinaceous protective colloid in basic form, said phenolic resin being characterized by:
 7. The method of claim 6 wherein said emulsion system additionally contains from 0.4 to about 20 weight percent of a dissolved ammonium salt of a strong inorganic acid. 